The present invention relates, in general, to a cooling device for an electric motor.
An electric motor of a type involved here generally includes a primary part and a secondary part which are disposed in opposite spaced-apart relationship to define an elongated air gap therebetween. The primary part is typically made of an iron body in the form of laminated electric sheets, and has slots for receiving current-carrying windings. Operation of the electric motor generates heat, in particular in the primary apart, which must be carried away to the outside. The dissipation of heat can be realized in a simple manner through heat conduction via metallic components of the motor, especially via the winding core, and subsequently through heat radiation and convection. Another approach involves the use of cooling elements such as serpentine cooling tubes which are integrated directly in the primary part or secondary part of the motor so as to directly carry away heat from the motor part being cooled via a coolant, such as water.
The use of an auxiliary cooling device has been proposed to assist the integrated cooling system or to provide a better cooling effect in the absence of an integrated cooling system in motor parts. This type of auxiliary cooling device is used, for example in a linear motor, and typically includes a carrier in the form of a trough or hat-shaped channel. The carrier has inner dimensions which conform to the outer dimension of the motor part being cooled. Disposed inside the carrier is a serpentine cooling tube which is secured by spring elements at least to the upper inner surface of the carrier. Optionally, an arrangement of insulating materials and insulating pieces is also provided. The so-assembled carrier is then mounted to the motor part to be cooled, normally the primary part, and secured by screw fasteners.
This type of auxiliary cooling device suffers shortcomings because the thermal coupling of the serpentine cooling tube to the structure being cooled is unsatisfactory. Moreover, as the motor parts, e.g., the primary parts, must be manufactured at precise dimensions, the need for additional, different components such as fastening screws, springs, insulations etc., in order to attach the cooling device to the motor part, adversely affects the precision of the outer dimensions, in particular in vertical dimension of linear motors or diameter of rotary motors, so that the required precision can no longer be ensured, or ensured only at great manufacturing costs.
It would therefore be desirable and advantageous to provide an improved cooling device for a motor part of en electric motor, which obviates prior art shortcomings and which is simple in structure and yet reliable and efficiently in operation, while still maintaining the dimensional accuracy of the motor part.